Clinical Characteristics of α-Blocker Responders in Men with Benign Prostatic Hyperplasia

Abstract

Background: Currently, α-blocker is becoming first-line drug therapy for benign prostatic hyperplasia (BPH). Although highly effective results are obtained with this therapy, a difference between the objective and subjective response rates is reported. To prevent unnecessary medical treatment and to predict the α-blocker response, we characterized the clinical features of α-blocker responders in men with BPH. Methods: Twenty-two men were consecutively enrolled in this study and received tamsulosin 0.2 mg once daily for 4–6 weeks. The primary measures of efficacy were maximum urinary flow rate (Q_max) determined from the flow measurements and international prostate symptom score (IPSS). Those with an increase in Q_max of ≧30% from baseline and a decrease in IPSS of ≧25% from baseline were defined as Q_max responders and IPSS responders, respectively. Clinical findings such as age, pretreatment IPSS and Q_max, serum prostate-specific antigen (PSA), total prostate volume, transition zone (TZ) volume, TZ index and T₂-weighted magnetic resonance image (MRI) of the prostate TZ were compared between responders and non-responders for both criteria. Results: In 17 of 22 (77.2%) patients IPSS improved by ≧25%. In 9 of 22 (40.9%) patients Q_max improved by ≧30%. There were no differences in clinical findings between IPSS responders and non-responders. On the contrary, Q_max responders showed smaller total prostate and TZ volumes, a smaller TZ index and a lower intensity of the TZ in MRI than Q_max non-responders. Conclusions: Determination of the prostate volume and MRI findings of the inner prostate gland were useful in predicting Q_max responders to the α-blocker in men with BPH. In contrast, there were no clinical characteristics of the IPSS responders. IPSS responders without a Q_max response should be closely followed while continuing the α-blocker therapy for a long duration.